This application is completely secure for downloading. 1&1 Telecom GmbH is the developer of the app which belongs to the Communication category. Google Play shows that 1&1 Mail is rated 4.2 by its users.
The latest release was on Mar 22, 2019 and this application was downloaded and installed by over 1M users. Samsung and HTC users recommend the app. Get the installation package of 1&1 Mail 4.2.3 that is absolutely free and take a look at users' reviews on Droid Informer.
Users write reviews pointing out that the app features such a drawback as an outdated design.